The present invention relates to a roll unit to be used in electrochemical surface treatments such as roughening treatment, rust prevention treatment, and oxidized surface treatment (blackening treatment) to be continuously performed on a surface of a rolled copper foil or an electrolytic copper foil, and in particular relates to a roll unit to be dipped in a surface treatment liquid.
In recent years, copper foil is being widely used in the manufacture of electronic components, wiring substrates and the like.
Generally speaking, an electrolytic copper foil is manufactured by using a rotating metal cathode drum and an insoluble metal anode (positive electrode) arranged at a position that is roughly at the lower half of the cathode drum and which surrounds the periphery of such cathode drum, electrodepositing copper on the cathode drum by flowing copper electrolyte between the cathode drum and the anode and applying a potential therebetween, and, upon achieving a prescribed thickness, peeling the electrodeposited copper from the cathode drum to continuously manufacture the copper foil.
In addition, the rolled copper foil is manufactured by repeatedly subjecting a melted and cast ingot to rolling and annealing a plurality of times.
As described above, the electrolytic copper foil and the rolled copper foil are continuously manufactured by being winded around a coil, and the obtained copper foils are used in a printed wiring board and the like by subsequently being subject to several chemical or electrochemical surface treatments.
Generally speaking, the electrochemical surface treatment of a copper foils is continuously performed by using a unit as shown in FIG. 1. FIG. 1 shows a lateral schematic diagram of a continuous surface treatment unit of a copper foil.
As shown in FIG. 1, a copper foil C winded around a coil (not shown) is continuously passed in front of opposing anodes B and subject to surface treatment via a plurality of upper rolls D arranged inside and outside an electrolytic tank A and a lower roll F. The surface-treated copper foil C is winded around the coil (not shown) once again. E is a guide roll. The lower roll F in the foregoing case is dipped in the surface treatment liquid.
The electrolytic tank is provided with an electrolytic solution for use in treatment such as a plating solution for roughening treatment and rust prevention treatment. The structure enables the circulation of the electrolytic solution that was replenished to or used as the initial make-up of electrolytic bath in the electrolytic tank. Current for surface treatment is flowed between the anode and the copper foil as the cathode.
As the anode, although an insoluble anode such as a Pb plate or a noble metal oxide coated Ti plate is usually used, a soluble anode which itself melts and is electrodeposited on the copper foil may also be used. This may be changed as needed according to the conditions of the electrochemical treatment.
Solutions such as copper sulfate and chromic acid are used in the electrochemical surface treatment, and the foregoing treatment solutions are highly corrosive. With the rolls used under the foregoing circumstances, there is a problem in that the treatment liquid will infiltrate into the bearing, and the bearing in particular is subject to severe abrasion and corrosion. Thus, devices have been made for filling grease into the bearing of the roll so as to inhibit the abrasion and to facilitate the replacement of the roll bearing, but such devices were insufficient.
In addition, although there is also a proposal of filling grease in the bearing as described above and providing an oil seal in order to inhibit the corrosion within the bearing, there was a problem in that the grease would leak from the bearing and flow to the roll main body and contaminate the roll.
In the conventional technology, a double seal structured leak prevention roll referred to as a plummer block is proposed for preventing the leakage of grease to the roll-side of transporting products (refer to Patent Document 1). Nevertheless, with this kind of structure alone it is not possible to prevent the infiltration of the treatment liquid in a corrosion environment, and it is thus unable to overcome the problem that the roll shaft is subject to severe abrasion. [Patent Document 1] Japanese Patent Laid-Open Publication No. H8-159163